The present invention relates to a pilot control valve especially for use in mining hydraulics with a valve insert configured as a valve cartridge which can be arranged in the valve accepting boring of a valve block or similar forming a multi-way valve whose valve housing has an inlet for pressure fluid, a connecting opening for a load, an outlet opening into a return feed and an axial boring for the acceptance of a valve closing body provided with a sealing surface, which can be lifted by means of a switching device fixed to the valve housing, against the return force of a spring from a valve sealing seat arranged between the inlet opening and the connecting opening, whereby with the lifting movement of the valve closing body from the valve sealing seat an at least two part closing mechanism arranged between the connecting opening and the outlet opening is coupled for their separation.
Previously proposed pilot control valves are employed in underground mining for the switching of main control valves arranged after them with which then hydraulic working cylinders of advancing support frames or other hydraulic equipment can be actuated. Due to the high working pressure and the corrosion promoting underground atmosphere, severe requirements are placed upon valves employed underground in respect of their switching power, switching distance and construction. In mining hydraulics the switching devices in the main comprise electromagnetic actuators which are designed to be intrinsically safe and are connected to corresponding electrical circuits. Using intrinsically safe electro-magnetic switching devices, the switching power which can be applied and the switching distance which is available for actuation is limited.
A previously proposed pilot control valve is known from DE 92 11 629 U1. It has a three part valve closing body which comprises two valve closing elements with cone shaped sealing surfaces and a coupling rod, which are accepted axially parallel to each other and with cone surfaces facing each other in a housing part comprising two valve housing parts screwed together to form a cartridge in which they can move too and fro. Each housing part has a valve seat associated with one of the closing surfaces and the distance of the valve seats from each other can be adjusted by the setting of the screw connection between the valve casing parts so as to facilitate an initial and subsequent adjustment of the valve setting. So that dependent upon the valve switching setting in the this pilot control valve a fluid current can take place between the high pressure line and the load or from the load to the return, both the coupling rods and also the valve closing elements are provided on their cylindrical outer surfaces with axially running flats or grooves, which at the same time limit and determine the cross section of flow and consequently the nominal bore of the pilot control valve. The manufacturing effort for the valve sealing elements comprising the valve sealing body and the coupling rod is therefore comparatively high and the functional integrity of this pilot control valve is dependent upon the precise adjustment of the separation of the two valve sealing seats.
It is an aim of the invention to produce a pilot control valve which has short switching paths, is simply constructed and has a simply produced valve sealing body in production engineering terms.